Wind Turbines – Components and Design Basics

Dr.-Ing. Stephan Matthiesen Project ManagementDipl.-Ing. (FH) Meik Schacknies Design DepartmentParis October 2009

Wind Turbines – Components and Design Basics

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Overview Part I

• Product range

• Components of a wind turbine


OverviewPart II

• Load assumptions for wind turbines

• Loads and load cases

• Rocking spring stiffness

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Rated power: 330 kWHub height: 44 – 50 m

Rated power: 900 kWHub height: 45 m / 55 m

Rated power: 800 kWHub height: 50 – 76 m

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Rated power: 800 kWHub height: 73 m

Rated power: 2.300 kWHub height: 64 – 113 m

Rated power: 2.000 kWHub height: 78 – 138 m

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Highest power producing WEC worldwide:

Rated power: 6.000 kW

Rotor diameter: 127 m

Hub height: 135 m

Power production: 20 Mio. kWh p.a.

• Produces electricity for more than 5000 households

• 35% more yield compared to predecessor - E-112

• Two-segment rotor blade facilitates transport

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-> blades

-> nacelle with generator and

hub

-> tower (steel / concrete)

-> electrical installation and

grid connection

-> foundation

-> with piles or soil improvement

(if necessary)

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-> blades

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-> nacelle

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-> steel tower

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-> concrete tower

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-> foundation with basket

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-> foundation with section

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-> foundation for concrete tower

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Overview Part I

• Product range

• Components of a wind turbine


OverviewPart II

• Design situations for wind turbines

• Loads and load cases

• Rocking spring stiffness

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Design situations

Environmental conditions

• Wind, Temperature, Ice, Earthquake

Operational conditions

• Normal operation and power production• Start up, shut down, idling, standstill

Temporary conditions

• Transportation of components• Installation and assembling• Maintenance and repair

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Design load cases

– Normal operation and normal external conditions

– Normal operation and extreme external conditions

• extreme wind speed• extreme direction change• extreme dynamic wind shear

– Fault situations and appropriate external conditions

• Control system fault• Electrical fault• Yaw system fault

– Transportation, installation and maintenance situations

wind directio

n

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Load cases for operational and environmental conditions defined in EN 61400-1

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[Hau 2005]

Due to the nature of wind the loads are high variable !

• mean wind, gravity loads (steady)

• turbulence, earthquake (stochastic)

• unbalanced mass, rotor frequency (periodic)

• start up / shut down, gusts (transient)

• Loads are calculated with special computation program in time domain.

• Load calculations have to determined for each type separately.

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Different aspects for structural design

1. Extreme Loads (Ultimate Limit State)

2. Fatigue Loads (Ultimate Limit State)

3. Stiffness of components (ULS and SLS)

- Vibrations (resonance effects)

- Deflections (distance between blade and tower)

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Vibrations - Rocking spring stiffness kφφφφ,dyn

To avoid resonance we have to consider the stiffness of the components but also the soil-structure interaction. The eigenfrequency of the system machine - tower – foundation - soilshall not be in the range of the variable frequencies. To ensure this requirement a minimum stiffness of foundation and soil is necessary.

Rotational spring stiffness

Mass of WEC

Tower

System:


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Eigenmodes of the tower structure

Important design parameter for WEC:

- Rotational frequency of rotor (1P)- Rotational frequency of one blade (3P)- Eigenfrequencies of the whole system (1. EF / 2. EF)

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Merci pour votre attention

Wind Turbines – Components and Design Basics

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